title: Reactive oxygen species modulate the differential expression of methionine sulfoxide reductase genes in Chlamydomonas reinhardtii under high light illumination.
abstract: Illumination of Chlamydomonas reinhardtii cells at 1000 (high light, HL) or 3000 (very high light, VHL) µmol photons m(-2)  s(-1) intensity increased superoxide anion radical (O(2)(•-)) and hydrogen peroxide (H(2)O(2)) production, and VHL illumination also increased the singlet oxygen ((1)O(2)) level. HL and VHL illumination decreased methionine sulfoxide reductase A4 (CrMSRA4) transcript levels but increased CrMSRA3, CrMSRA5 and CrMSRB2.1 transcripts levels. CrMSRB2.2 transcript levels increased only under VHL conditions. The role of reactive oxygen species (ROS) on CrMSR expression was studied using ROS scavengers and generators. Treatment with dimethylthiourea (DMTU), a H(2)O(2) scavenger, suppressed HL- and VHL-induced CrMSRA3, CrMSRA5 and CrMSRB2.1 expression, whereas H(2)O(2) treatment stimulated the expression of these genes under 50 µmol photons m(-2)  s(-1) conditions (low light, LL). Treatment with diphenylamine (DPA), a (1)O(2) quencher, reduced VHL-induced CrMSRA3, CrMSRA5 and CrMSRB2.2 expression and deuterium oxide, which delays (1)O(2) decay, enhanced these gene expression, whereas treatment with (1)O(2) (rose bengal, methylene blue and neutral red) or O(2)(•-) (menadione and methyl viologen) generators under LL conditions induced their expression. DPA treatment inhibited the VHL-induced decrease in CrMSRA4 expression, but other ROS scavengers and ROS generators did not affect its expression under LL or HL conditions. These results demonstrate that the differential expression of CrMSRs under HL illumination can be attributed to different types of ROS. H(2)O(2), O(2) (•-) and (1)O(2) modulate CrMSRA3 and CrMSRA5 expression, whereas H(2)O(2) and O(2)(•-) regulate CrMSRB2.1 and CrMSRB2.2 expression, respectively. (1)O(2) mediates the decrease of CrMSRA4 expression by VHL illumination, but ROS do not modulate its decrease under HL conditions.
authors.affiliation: Institute of Marine Biology, National Sun Yat-sen University, Kaohsiung, 804, Taiwan; Department of Marine Biotechnology and Resources, National Sun Yat-sen University, Kaohsiung, 804, Taiwan; Doctoral Degree Program in Marine Biotechnology, National Sun Yat-sen University, Kaohsiung, 804, Taiwan; The Asia-Pacific Ocean Research Center, National Sun Yat-sen University, Kaohsiung, 804, Taiwan.
authors.forename: Hsueh-Ling
authors.initials: HL
authors.lastname: Chang
authors.forename: Yu-Lu
authors.initials: YL
authors.lastname: Tseng
authors.forename: Kuan-Lin
authors.initials: KL
authors.lastname: Ho
authors.forename: Shu-Chiu
authors.initials: SC
authors.lastname: Shie
authors.forename: Pei-Shan
authors.initials: PS
authors.lastname: Wu
authors.forename: Yuan-Ting
authors.initials: YT
authors.lastname: Hsu
authors.forename: Tse-Min
authors.initials: TM
authors.lastname: Lee
mesh_terms: D016825:Chlamydomonas reinhardtii / Q000201:enzymology / Q000235:genetics* / Q000378:metabolism; D004307:Dose-Response Relationship, Radiation; D015971:Gene Expression Regulation, Enzymologic / Q000528:radiation effects; D018506:Gene Expression Regulation, Plant / Q000528:radiation effects; D006861:Hydrogen Peroxide / Q000378:metabolism / Q000494:pharmacology; D007527:Isoenzymes / Q000235:genetics; D008027:Light; D051150:Methionine Sulfoxide Reductases / Q000235:genetics*; D016877:Oxidants / Q000378:metabolism / Q000494:pharmacology; D010940:Plant Proteins / Q000235:genetics*; D017382:Reactive Oxygen Species / Q000378:metabolism*; D013481:Superoxides / Q000378:metabolism; D059467:Transcriptome / Q000528:radiation effects*
chemical_list: D007527:Isoenzymes; D016877:Oxidants; D010940:Plant Proteins; D017382:Reactive Oxygen Species; D013481:Superoxides; D006861:Hydrogen Peroxide; D051150:Methionine Sulfoxide Reductases; C027219:methionine sulfoxide reductase